Hi,

 Here's v5 of the outstanding fixes for Oxford Semiconductor 950 UARTs 
including most updates requested by Andy (thanks for your review!).  

 Also while looking into an unrelated issue I have come across the 
DIV_ROUND_CLOSEST macro and updated 5/5 replacing equivalent handcoded 
calculations.  I have verified that there is no change in machine code 
produced after this update with the i386 and RISC-V targets.

 Please apply.

  Maciej